tcp: md5: check md5 signature without socket lock

Since a8afca032 (tcp: md5: protects md5sig_info with RCU) tcp_md5_do_lookup
doesn't require socket lock, rcu_read_lock is enough. Therefore socket lock is
no longer required for tcp_v{4,6}_inbound_md5_hash too, so we can move these
calls (wrapped with rcu_read_{,un}lock) before bh_lock_sock:
from tcp_v{4,6}_do_rcv to tcp_v{4,6}_rcv.

Signed-off-by: Dmitry Popov <ixaphire@qrator.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 6 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 22055b0..f2ce955 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -667,7 +667,8 @@ clear_hash_noput:
 	return 1;
 }
 
-static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
+static int __tcp_v6_inbound_md5_hash(struct sock *sk,
+				     const struct sk_buff *skb)
 {
 	const __u8 *hash_location = NULL;
 	struct tcp_md5sig_key *hash_expected;
@@ -707,6 +708,18 @@ static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
 	}
 	return 0;
 }
+
+static int tcp_v6_inbound_md5_hash(struct sock *sk, const struct sk_buff *skb)
+{
+	int ret;
+
+	rcu_read_lock();
+	ret = __tcp_v6_inbound_md5_hash(sk, skb);
+	rcu_read_unlock();
+
+	return ret;
+}
+
 #endif
 
 static void tcp_v6_init_req(struct request_sock *req, struct sock *sk,
@@ -1247,11 +1260,6 @@ static int tcp_v6_do_rcv(struct sock *sk, struct sk_buff *skb)
 	if (skb->protocol == htons(ETH_P_IP))
 		return tcp_v4_do_rcv(sk, skb);
 
-#ifdef CONFIG_TCP_MD5SIG
-	if (tcp_v6_inbound_md5_hash(sk, skb))
-		goto discard;
-#endif
-
 	if (sk_filter(sk, skb))
 		goto discard;
 
@@ -1424,6 +1432,11 @@ process:
 	if (!xfrm6_policy_check(sk, XFRM_POLICY_IN, skb))
 		goto discard_and_relse;
 
+#ifdef CONFIG_TCP_MD5SIG
+	if (tcp_v6_inbound_md5_hash(sk, skb))
+		goto discard_and_relse;
+#endif
+
 	if (sk_filter(sk, skb))
 		goto discard_and_relse;